Missing FieldError.Field() and 'Key' in ValidationErrors Returned from Var() and ValidateMap()

[neiljpowell]

• [ x] I have looked at the documentation here first?
• [ x] I have looked at the examples provided that may showcase my question here?

Package version eg. v9, v10:

v10

Issue, Question or Enhancement:

Issue: The FieldError.Field() is empty and not populating the ValidationErrors key for Error(). Consistent ValidationError messages and translation are important and should be a priority to implement. Allowing a field name/key to be passed as a argument to Var() and ValidateMap() would be great. It would also eliminate a lot of unnecessary structs added to code just for producing proper error messages.

There several Issues reported already #425 #805 #894 #1284 and at least one PR #962 to fix.

Code sample, to showcase or reproduce:

func TestValidator_VarAndMapValidationErrors(t *testing.T) {

	validtr := validator.New()
	testVar := ""
	//test validation failure
	err := validtr.Var(testVar, "required")
	for _, fieldError := range err.(validator.ValidationErrors) {
		t.Logf("Var - Name: '%s', Tag: '%s'", fieldError.Field(), fieldError.Tag())
		t.Logf("Var - Error: '%s'", fieldError.Error())
	}
	//Output:
	// Var - Name: '', Tag: 'required'
	// Var - Error: 'Key: '' Error:Field validation for '' failed on the 'required' tag'

	var testData = map[string]interface{}{"testVar": testVar}
	var testRules = map[string]interface{}{"testVar": "required"}

	errs := validtr.ValidateMap(testData, testRules)
	for _, err := range errs {
		for _, fieldError := range err.(validator.ValidationErrors) {
			t.Logf("Map - Name: '%s', Tag: '%s'", fieldError.Field(), fieldError.Tag())
			t.Logf("Map - Error: '%s'", fieldError.Error())
		}
	}
	//Output:
	// Map - Name: '', Tag: 'required'
	// Map - Error: 'Key: '' Error:Field validation for '' failed on the 'required' tag'
}